1. Field Of The Invention:
The present invention relates generally to aircraft tires and associated landing gear apparatuses which rotate a wheel of a landing aircraft prior to contact between the wheel and a runway.
2. Description Of The Prior Art:
Prior to impact with a runway, the wheels of a landing aircraft are not rotating. When the wheels meet the runway, they must quickly accelerate to match the speed of the aircraft. Until they match this speed, the runway abrades rubber from the tires. As a result, the aircraft's tires must be repaired or replaced frequently. The rubber abraded from the tires is deposited on the runway as a long skid mark. These rubber deposits build up over repeated landings and must be periodically removed.
One method of alleviating these problems is to rotate a landing aircraft's wheels prior to the wheels contacting a runway. Various apparatuses for rotating an aircraft wheel or wheels prior to landing have been suggested.
U.S. Pat. No. 3,529,792 discloses an aircraft tire provided with wedge-shaped bar structures on the sidewalls thereof. Impingement of the air flow on front bar faces at the bottom of the tire sets the wheels to rotating prior to touchdown of the aircraft.
U.S. Pat. No. 3,773,283 discloses an aircraft tire with circumferential grooves in the tread face. The grooves include as the floor thereof a series of impeller vanes defined by assymmetrical wedges which present differential resistance to the airstream at vertically opposed locations on the tire and cause the tire to be rotated by the airstream.
U.S. Pat. No. 3,814,354 discloses a power operated device associated with the conventional landing gear of an aircraft for causing rotation of the landing wheels of the aircraft by the airstream moving past the aircraft prior to landing and while still airborne.
U.S. Pat. No. 4,061,294 discloses an aircraft wheel rotator. The rotator provides an air collector which is similar to a plow and which forces air outwardly and downwardly to impinge on the spokes of the landing wheel with which the air collector is associated. The spokes are formed as the blades of a turbine to be driven by the air from the air collector.
U.S. Pat. No. 4,385,739 discloses a system for causing an airborne vehicle's wheels to rotate prior to contacting the runway surface upon landing. Means are provided for diverting a stream of air from an aircraft's engines or other sources against the radially spaced surfaces of the mechanical housings which are affixed to the wheels. This forces the wheels to rotate.
Means for rotating aircraft wheels have also been disclosed to alleviate other problems associated with aircraft landings. U.S. Pat. No. 3,568,747 discloses an improved form of pneumatic aircraft tire which may assist in avoiding several problems associated with landing on a wet runway. The pneumatic tire comprises a tread portion and two shoulder portions, at least one of which is provided with a plurality of generally radial and axially outwardly extending faces projecting into the region adjacent to the tire shoulder. The faces are disposed so that they will be engaged by water on the runway and decrease the relative velocity of the tread portion and the surface during landing.
In spite of these known systems, there remains a need for a commercially acceptable apparatus for rotating a wheel of a landing aircraft prior to contact between the wheel and a runway.